Foot-and-mouth disease remains a threat to North American livestock

North America needs to prepare better for an outbreak of this economically important disease

Foot-and-mouth disease virus and the disease it causes have been intensively studied for decades. Although we know a great deal about the virus and vaccines used to prevent foot-and-mouth disease, it remains endemic across large parts of Africa, South America, the Middle East and Asia, and is a constant threat to North America. Globally, it is the most economically important infectious disease of livestock, affecting cattle, pigs, sheep and goats and other cloven-footed animals. At any point in time, foot-and-mouth disease is endemic in 100 countries, globally.

Related Articles

Farmer and veterinarian talking in a barn with cows in the back.

Potentially crippling trade-related losses force foot-and-mouth disease-free countries to strictly enforce measures to retain their free status and develop elaborate response plans should it come ashore. The U.S. has experienced foot-and-mouth nine times since 1870. Strict slaughter and quarantine measures helped eradicate the disease. The last foot-and-mouth outbreak in the U.S. occurred near Montebello, California, in 1929. Hogs contracted the disease after being fed swill with meat scraps from a tourist steamship coming from Argentina. Canada has been free of foot-and-mouth since 1952, following exposure of swine to imported sausage by a farm labourer from Europe. Mexico has been foot-and-mouth-free since 1953.

Dustin Baker, deputy director of economics and domestic production issues for the U.S. National Pork Producers Council, maintains an outbreak of foot-and-mouth disease in the U.S. would be catastrophic. Beef and pork export markets would collapse, Baker says, driving down demand for corn, soybeans and other feed grains. Beef, pork, corn, soybeans, and the poultry industry would all be affected with a decade-long economic impact of over $200 billion, Baker adds.

Reason enough that beef and pork producers are putting considerable pressure on politicians in the U.S. to re-examine how vaccine banks for foreign animal diseases need to be financed and managed. Canada needs to closely follow what’s happening stateside and follow suit.

According to the USDA, the agency does not have sufficient supplies of foot-and-mouth vaccine to control more than a small outbreak. A government accountability office claims limited resources prevent adequate manufacturing, storage and distribution of vaccine. They state that current U.S. vaccine supplies would only be sufficient to control foot-and-mouth in about 14 per cent of Texas’s cattle or about four per cent of Iowa’s swine herd. These states represent the nation’s largest cattle and swine populations. Canada’s ability to access sufficient foot-and-mouth vaccine could be compromised in a cross-border outbreak, a distinct possibility with the present dynamics of the North American meat and livestock trade.

The Canadian government recognizes that rapid slaughter and disposal of livestock, consistent with the traditional “slash and burn” approach, may be hampered by technical and logistical problems, or by legal restrictions imposed by an intolerant public, making vaccination part of a mandatory control strategy.

Under a contractual agreement established in 1982, the governments of Canada, the United States, and Mexico established a vaccine bank (called the Bank) to provide rapid access to killed vaccines of proven safety and potency, should vaccine be needed to deal with an outbreak of foot-and-mouth. Each country contributed US$0.5 million per year to maintain the Bank. The Bank, which is physically located in the United States, holds viral antigens of several strains of foot-and-mouth disease virus, which are re-evaluated periodically in relation to global developments. The 37-year-old agreement has been reviewed on an ad hoc basis.

If a foot-and-mouth outbreak occurred in North America, the chief veterinary officers of the three countries would activate the Bank. The strain of virus involved in the outbreak would be compared with antigens held in the Bank. An antigen concentrate judged to be protective against the field strain would be sent to a contracted company for finishing (diluting the concentrate to final doses of vaccine, adding adjuvant, bottling, and labelling), with the view to supplying a predetermined number of vaccine doses within several weeks.

If vaccines held in storage were judged not to be protective, the Bank could send the field virus to a commercial contractor to develop suitable vaccines.

Current strategies for co-ordinated diagnostic support, vaccine distribution, storage and administration similar to the U.S. National Veterinary Stockpile concept may fall short. The National Veterinary Stockpile is a national repository of critical veterinary supplies, equipment and services to be deployed within 24 hours. It is to contain enough animal vaccine, antiviral, or therapeutic products to respond to the most damaging animal diseases affecting human health and the economy. But it has not received sufficient funding to carry out its directive.

A coalition of U.S. agricultural organizations has expressed serious concern that the current vaccine bank and USDA’s ability to scale up vaccine production in an emergency are not adequate for addressing a medium to large foot-and-mouth outbreak. Canada has always been on the outside looking in.

The lag time from the onset of an outbreak until finished vaccine is delivered to the field may take weeks for a small outbreak and months for the number of doses needed for a large outbreak. Of equal concern is the limited number of antigen strains maintained at facilities in Canada and the U.S. As well, antigen concentrates have a limited shelf life, affecting potency of the finished vaccine. They must be routinely adjusted or replaced.

The surge capacity for approved manufacturers worldwide is also a concern. There is no ability to produce the millions of doses needed in the event of a large-scale outbreak in North America. The companies that currently produce vaccine for regular customers have advised U.S. representatives that they will not abandon regular clients to produce vaccine on-demand for the U.S. Any ongoing trade discord would complicate Canada’s ability to access vaccine if needed.

Contracts for offshore foot-and-mouth vaccine banks providing vaccine antigen concentrates for all foot-and-mouth strains currently circulating in the world need to be examined. Request for proposals from companies regularly engaged in foot-and-mouth vaccine production should be in-hand and budgeted for.

Mechanisms should be established for how the livestock industry might share the cost of maintaining vaccine banks. A means of equitable vaccine distribution between industry sectors and regions in the event of an outbreak needs to be part of the planning process.

The livestock industry must keep management of foot-and-mouth vaccines on the agenda with regulatory organizations at all times. Having effective vaccines available, to control and eradicate foot-and-mouth, are an ever-present cost of doing business in a modern world.

Dr. Ron Clarke is a veterinarian who consults on animal health and disease issues and writes for agricultural and veterinary audiences.

About the author

Columnist

Dr. Ron Clarke prepares this column on behalf of the Western Canadian Association of Bovine Practitioners. Suggestions for future articles can be sent to Canadian Cattlemen ([email protected]) or WCABP ([email protected]).

Comments

explore

Stories from our other publications